This project is designed to yield new information about an H-2-linked gene which affects the susceptibility of mice to cortisone-induced cleft palate. We propose to map this gene more precisely by testing a number of congenic strains of mice which have H-2 chromosomes that are recombinants between high and low susceptibility haplotypes. Preliminary evidence suggests that the gene maps between H-2K and the T locus, so experiments have been designed to analyze this genetic region closely. DNA polymorphisms that have been mapped to the region between H-2K and T will be studied in congenic lines that are informative with respect to cleft palate susceptibility. There is also evidence that an H-2-linked gene affects the susceptibility of fetal mice to the masculinizing and feminizing effects of sex steroids. We propose to map this gene more precisely, and to determine whether it differs from the gene which controls cleft palate susceptibility. Finally, we propose to determine whether the susceptibility of mice to sex steroid - induced lymphocyte depletion is affected by H-2-linked genes.